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area utilize leach lines or filter beds; one system utilized a shallow sump. The septic permits can be found in Appendix 4 of this report. Expected On-Site Maximum Septic Tank Usage Maximum expected usage on the Site would be from the existing residents and proposed employees and customers of Bella Gardens. Septic system design should be based on the San Joaquin County On-Site Wastewater Treatment Systems Standards (2017) or other engineering recommendations. Ground Water Information Depth and Gradient Live Oak reviewed ground water elevation information available from the San Joaquin County Flood Control and Water Conservation District to determine the ground water levels near the Site. Data from spring and fall of 2016 were the most recent available from this source. According to an analysis of these maps (Plates 5 and 6), ground water elevation is approximately 18 to 22 feet below mean sea level; the ground-water flow is to the north or southwest at a rate of approximately two to five feet per mile, depending on the season. Given that the ground elevation of the Site is approximately 31 to 35 feet above sea level, based on the County ground water maps the depth to ground water below the Site is estimated to range between nine to 17 feet. San Joaquin County experienced its highest recent ground-water levels in 1983 and 1999. Review of spring ground-water maps for these years (Plates 7 and 8) reveals that depth to water would have been approximately 10 feet; the Site is just beyond the mapped area but closest to the 10-foot contour. Potential Ground Water Contamination Issues The Soil Suitability Study is not intended to be an investigation into ground-water contamination sources, and no such investigation was conducted. Many sources can contribute to ground water contamination, including leaking underground storage tanks, agricultural activities, dairies, septic systems, and storm water infiltration. Agricultural activities and the use of septic systems in the area are known ground water contamination sources with the potential to impact the Site. Two common ground-water contaminants in San Joaquin County are nitrate and dibromochloropropane (DBCP). Live Oak reviewed the San Joaquin County Environmental Health Department's maps of Nitrate — Land Use Data and DBCP— Land LOGE 1908 Page 3